1. Field of the Invention
The present invention relates to a door window regulator which vertically moves and guides a door window glass of an automobile.
2. Description of the Prior Art
In general, a door window regulator has an X-shaped arm made from steel sheet and is arranged such that a door window glass mounted on the upper end of the X-shaped arm is vertically moved by the pivoting of the X-shaped arm. The door window regulator employing such an X-shaped arm has a relatively large weight and a relatively large moving locus, which fact disadvantageously limits the range of available configurations and structures of the door.
In view of this fact, door window regulators have heretofore been proposed in which a wire is employed as a window glass driving means mainly from the viewpoint of reducing the weight of the apparatus.
Such conventional door window regulators include those shown in the specifications of Japanese patent Laid-Open No. 161,173/1980, Japanese Utility Model Laid-Open No. 41,996/1980 and West Germany Patent Laid-Open No. 3,108,557. In these prior arts, pulleys are rotatably supported at the respective upper and lower portions of a guide which is adapted for guiding the vertical movement of a window glass, and a wire is passed over these pulleys to thereby transmit driving force to the window glass.
These door window regulators, however, involve the following problem. The respective axes of the upper and lower pulleys extend parallel to each other and in the lateral direction of the vehicle, that is, in the direction orthogonal to the plane of the window glass. On the other hand, the longitudinal axis of the portion of the wire which extends from each of the pulleys to a driving unit is offset from the plane of rotation of the pulley. In consequence, the wire strongly presses against the side surface of the pulley groove, thus increasing the amount of friction occurring therebetween. This obstructs smooth rotation of the pulleys, causes the pulleys, the pulley shafts, the wire and so forth to become worn and consequently hinders smooth vertical movement of the window glass.